Field
The present disclosure relates to power amplifiers in radio-frequency (RF) applications.
Description of the Related Art
Many devices, such as wireless devices, require or utilize a cascode amplifier structure to decouple performance-degrading thermal protection solutions from high performance radio-frequency (RF) power array elements.
In some applications, thermal ruggedness can be built into an array by increasing distances between devices in the power array, and by through ballasting techniques. Such techniques can introduce local feedback at each of the devices within the power array.
Spreading of the array can reduce the heating of adjacent array elements and can effectively reduce the thermal resistance of the array to heat sinking structures. Such a technique can result in an increased area for the array, and can also increase the corresponding die size and cost.
Ballasting techniques are often in the form of emitter degeneration or base degeneration. These solutions can introduce loss in the RF signal path which can degrade gain, efficiency and saturated power, thereby reducing performing. Other solutions which utilize a cascode architecture may include a common connection of the cascode emitters, which typically involves ballasting of the cascode devices to prevent thermal run-away.